﻿using System;
class Solution
{
    static void Main()
    {
        Console.Write("请输入学生成绩：");
        int score = int.Parse(Console.ReadLine());

        if (score >= 90)
        {
            Console.WriteLine("A");
        }
        else if (score >= 60 && score <= 89)
        {
            Console.WriteLine("B");
        }
        else if (score < 60)
        {
            Console.WriteLine("C");
        }
    }
}
